1. Field of the Invention
The present invention relates to the field of ornamental landscaping and aqua-culture and, in particular, to a filter system to efficiently, mechanically filter and remove solid wastes, biologically converting harmful chemicals and toxins to a safe and fish-healthy environment.
2. Background Description
For many years fish pond owners have tried to find an easy way to clean and maintain their ponds. Water quality is the utmost important issue to all pond keepers. Without an adequate filtration system two things happen: One, the water will not stay clear. Decomposing or decaying debris, plants, or any organic matter will cloud the water, release toxic gases into the water, and consume oxygen. This promotes algae growth which in turn consumes even more oxygen from the water. Two, fish waste also produces toxins, and consumes oxygen and organic matter, thereby drastically reducing water quality. Without an adequate filtration system the fish will literally die in their own waste.
The most common filter is the simple up-flow filter—a large box filled with gravel or lava rocks. Water enters the bottom of the box and filters up through the gravel bed and then returns to the pond. It works reasonably well for a large pond with a small number of fish and is relatively inexpensive to build. However, cleaning a simple up-flow filter is untidy and inconvenient.
Designs of filters have advanced from the simple filter box to elaborate vortex chambers, settling tanks, tank after tank of filter pads, brushes (as mechanical and biological materials), to pressurized chambers. The quest for a better filter, one that not only cleans and filters water, but also provides convenience, requires less time to clean, and that is energy efficient goes on.
Pond owners have turned away from filter pads, which are dirty, messy, and require frequent attention, and moved to sealed pressurized tank systems with quick and easy-to-use multi-port control valves similar to those in sand filters. With the turn of a handle, the owner can quickly change the filter to cleaning mode, or vice versa.
Initially, sand filters were used for sealed pressurized tank systems. Using densely packed sand as a filter media, these systems provided an excellent means of removing dirt, debris, and organic materials. Sand also provided a large surface area which assisted biological filtration. However, there are three major drawbacks in using sand as a filter.
First, the sediments collected at the top layer of the sand often cake up and the water will find its way to the bottom of the filter by channeling through the sand. This renders the biological filtration ineffective. Second, sand requires frequent backwashing (as often as 2 to 3 times per day with heavy fish loads), which can be a great inconvenience. Finally, sand filtration requires a powerful water pump to push water through the sand bed. A suitable pump consumes considerable electrical energy.
More recently, pond-keepers have turned to “beads,” another filter media, to clean and maintain their ponds. Beads are small and spherical in shape. Although beads do not quite match the filtration capabilities of sand, a bead filter still provides reasonable mechanical and biological filtration. It is more desirable because it offers greater convenience, reducing backwashing to only a few minutes every 7 to 10 days, and requires a smaller, more energy efficient pump.
A bead filter in a sealed pressurized tank contains a large number of small diameter plastic beads. The beads form a packed bed inside the filter that provides mechanical and biological filtration. Originally developed for the commercial aqua-culture industry, this type of filter is ideal for ponds with a large fish population. The common purpose of the many bead filters available today is to provide pond owners the most reliable, low-maintenance operation possible. However, there are still a few design limitations to the current state-of-the art systems available.
The “Bubble Bead Filter”, manufactured by Fluid Arts since 1995, was one of the first bead filters on the market. The concept of floating material that could pack together in a very dense manner as a filter media and yet could be broken apart when cleaning was a needed revolution for the pond filter industry. This particular bead filter occupies a small footprint, (about four square feet at most) and is easy to clean. With blower systems, one can thoroughly remove all waste collected with a few steps.
The Bubble Bead Filter has the shape of an hour-glass Water enters at the bottom of the tank and exits at the top. In backwash mode, the pump is turned off, so no pond water enters the filter. A drain valve located at the bottom of the filter is opened to allow the water inside the filter to carry dirt and debris out of the tank through a drain. As the water level inside the filter tank lowers through the narrower neck of the hourglass shape, the beads which became packed during the filtering operation are broken up. This “unpacking” loosens up the dirt and debris from the beads as water is drained from the tank. After draining, the drain valve is shut off, the pump is turned back on, and the container is filled up again. The backwashing mode is repeated 3 or 4 more times—or until the waste water becomes reasonably clear. This mode of cleaning of the filter requires time and considerable water.
The “Aqua Dyne Bead Filter” (AquaDynamite, Inc.) was introduced by Koi Camp in 1998. Although this filtration system uses a swimming pool filter, and, in fact, is built from the same tank and external fittings, it has been completely re-engineered internally. The diffuser column was fabricated with a multi-port control valve. With a turn of a handle on the control valve, the filter can be switched quickly to different modes, such as filtration, back-wash, re-circulation, waste, and so on. Water enters and exits through an easy-to-use multi-port valve. Attached to the bottom of the multi-port valve is a low friction central diffuser column that virtually eliminates the frequent clogging associated with other bead systems on the market. With the control valve set to filter, the water flows out of slots at the bottom of the diffuser column, passes through the floating beads where it is mechanically strained and biologically filtered, and then flows through slots at the top of the diffuser.
Unfortunately, there are several undesirable traits of these bead systems:
1) Over time, dirt, debris and other organic materials cause the floating beads to stick together and normal back-washing does not effectively remove all of the debris strained by the beads. Thus, especially in large tanks, a high flow volume air blower must be used to “unpack” the beads. This can create problems if the air blower is left on too long, (more than the seven minutes recommended by the manufacturer).
2) The air rising from the bottom to the top of the filter creates turbulence that scrubs away some of the beneficial bacteria on the surface of the beads. This causes a spike in ammonia and nitrite levels in the pond water that is considered stressful and may be dangerous to fish health. This elevated level of ammonia and nitrite in pond water may last as long as 3 to 5 days before filtration reduces it to a tolerable level. While the tight packing of the beads provides cleaner water, it also requires frequent cleaning of the filter every 7 to 10 days. So, while the bead filter is efficient, it also purges useful bacteria, limiting the overall effectiveness of the bead filter's biological filtration.
3) Bead media have a smooth outer surface and over time bacterial growth begins to form layers. The first layer of bacteria can be encapsulated by newer growth and can become anaerobic. This can impact fish health by consuming oxygen, lowering the pH level, increasing stress, and emitting harmful toxins into the water as underlying layers of bacteria decay.
4) Bead media are uniform in size. Thus they tend to pack uniformly, resulting in water channeling through the bead bed that greatly reduces filtering effectiveness.
Recently, the industry has turned to hollow plastic tubular media. Hollow plastic tubular media have several advantages over bead media. First, they eliminate water channeling through the media bed due to the random orientation of individual units. Second, water travels on the surface of the tubular media as well as through the hollow inner space of the media. Better circulation means more oxygen for bacterial growth. Third, the ribbed outer surface of tubular media preserves the bacterial bio-film, and the intricate configuration of the inner surface adds even more opportunity for biological activities. Fourth, the ribbed outer surface creates a tighter interstitial spacing between adjacent media and interlocking media surfaces result in better entrapment of solids. Finally, if the density of the plastic material used is the same as that of water, and the media are neutral in buoyancy, the tubular media will settle against the water flow (upward or downward) forming a dense packing within the tank. In the backwash mode, hollow plastic tubular media are easy to unpack. By reversing the water flow, without the use of an air blower, the media bed can be fluidized, trapped solids unclogged and the dirty water is directed to the waste line. Cleaning of the filter is accomplished by backwashing the filter, when the media is stirred and the dirt is flushed out with internal water jets.
Current tubular media have overcome problems with water channeling, and with removal of bacteria during the backwash cycle. However, current systems using hollow plastic tubular media continue to have a number of additional deficiencies:
First, current systems continue to use components of a sand filter which have the diffuser column consisting of a number of lateral slot that have openings that are small, thus preventing the sand from passing through. This results in rapid clogging when the diffuser is used as a pond filter.
Second, the strainer does not have sufficient openings to allow the dirt to be removed from the filter bed quickly. Consequently, current systems consume a significant amount of water in backwashing the media bed. Furthermore, the openings in current systems are small circles, and this has the unfortunate effect of creating a water jet that stirs up the biological media at the top of the tank.
Third, a first diffuser head (with multiple lateral slots) is located at the bottom of the filter tank and a second diffuser head (generating spiral water jets) is located at the middle of the diffuser column. During backwash, the water is divided into two portions. One provides water to the laterals located at the bottom of the filter tank, lifting the media bed and dislodging dirt and debris from the media bed. At the same time, the combination of the second diffuser's water jets with the lateral jets at the bottom will stir the media bed in an upward spiral motion. This movement of the media bed further dislodges dirt and debris trapped within the media bed and directs the dirt and debris to the waste line through the multi-port valve. This diffuser column configuration has several disadvantages. Since the water is divided into two portions, the water that exits at the second diffuser head may not provide sufficient pressure in order to effectively stir and agitate the entire media bed. Also, the water that exits through the lateral slots at the bottom of the filter tank will not have enough water flow volume to rapidly dislodge dirt within the lower portion the media bed. Thus it will take more water to clean the entire media bed, resulting in energy inefficiency.
Fourth, the bio media is made of ABS plastic, a sinking type of bio media which requires more energy to clean, and is not made to be used for retrofitting of any bead systems on the market.